docs: def get_value_in_base_currency(self) -> Decimal:
          """ Calculates the value of security holdings in base currency """
          # check if the currency is the base currency.
          amt_orig = self.get_value()
          # Security currency
          sec_cur = self.get_currency()
          #base_cur = self.book.default_currency
          cur_svc = CurrenciesAggregate(self.book)
          base_cur = cur_svc.get_default_currency()
  
          if sec_cur == base_cur:
              return amt_orig
  
          # otherwise recalculate
          single_svc = cur_svc.get_currency_aggregate(sec_cur)
          rate = single_svc.get_latest_rate(base_cur)
  
          result = amt_orig * rate.value
          return result